Ok guys, I need some ideas. Here's what my camaro is doing. Sometimes when I am letting it idle, it will idle too low, around 490 or so while in drive. It will start getting a little rough at that rpm naturally. However, after running for a good bit and warmed up, it will maintain a nice 550 while in drive. BUT, when i turn on the defrost, or the blower motor, SOMETIMES the voltmeter will drop well below the half way mark (somewhere around what would be like 9 volts. And it stays like that unless I turn the defrost off, or whatever has drawn the power. Now, my car never gives me starting porblems, it always has a strong crank, and I just replaced the alternator assuming that was the problem. (Alternator looked older than dirt, so I figured I'd replace it regaurdless.) I got a AC Delco alternator, and my battery is AC Delco as well. Seems this hasn't taken care of the problem. Any ideas? (Electrical is not my strong point, lol. )

Thanks and Happy Thanksgiving!

 

The best places to start trouble shooting the charging system are at the battery and alternator. Check voltage at both locations and see what you come up with. I wouldn't bother load testing the battery since it should be fine considering it's new, but by checking voltage in both locations you will find out if you have any wiring issues if your alternator is producing enough power (ie bad grounds, etc)

 

Thanks for the advice Gummie, but one quick thing i gotta point out. It's my alternator that is new. The battery is a little older, but not by much. I guess I outta check out all the connections again. Like i said, i doubt its my battery cause if it was weak, normally you'd think it wuld die after a few days of me not running the car, which hasnt been a problem. the car always cranks strong and never acts like its dying. just this insane current draw from my blower motor and rear defrost. the rear defrost especially. and with it being intermittent and all, its confusing the heck outta me.

 

The idea being to find out how much current/voltage is being lost between the battery/alternator and whatever's getting the power You could also check against your gauge to see how accurate it is. You shouldn't be dropping that far with that kind of load.

 

Ok. Im pretty sure the gauge is fine, because everything dims for a sec when i turn the defrost on.

 

I also doubt your dash Volts gauge reading of 9 volts.
After 20+ years, the dash gauges are often un-accurate. It can be due to bad electrical and ground connections that lead up to the dash, not the gauge itself.
You need to use a handheld voltmeter and check the actual voltage at the Alt and battery.

If the car's voltage really dropped this low, your lights would STAY dim, not just dim for a split second (normally it takes a moment for the voltage regulator to adjust to a large load being applied to the Alt).

Without getting your hands on a voltmeter to troubleshoot what is really happening, all you can do is guess.

 

It's normal for the guage to drop down quite far with a heavy load. The CS gen will only put out about 25-35 amps at idle. The guage should go up when you start to drive. With a stock gen and good battery with the blower on and rear defroster and lights even the turn signal flasher will slow down and if you look close the tach will bounce to the rythm of the turn signals. I wrestled with this on my 89 and the only solution was I changed my gen to a CS 130D. The D has a more aggressive charging curve at low rpm and solves this issue. Also the guage can be reading low. Pull off the bezel and remove the fasteners that hold the guage in. Pull the guage out and you will see the use the threads as connections to the panel pc board. Remove the two nuts that hold on the ceramic resistor on the guage and clean the contact points on the block with alcohol. Reinstall the nuts(don't overtighten or Y can crack the resistor) and clean the fingers where the guage plugs in with a Q tip with a little WD. Also clean the guage threads then reinstall. If the guage is reading low it will correct this.

 

Don't overlook belt tension and condition, #1 cause of what appears to be a charging failure.

 

thanks for all responses guys. Belt tension is the first thing i originally checked before just saying heck with it and got a new alternator. Well, turns out it wasn't the alternator. So, I need to look elsewhere, but its not causing my car to run bad or go dead, so screw it for now. lol.